1. Field of the Invention
The present invention relates generally to a multiple extension telescoping boom apparatus and, more particularly, to a color coded boom and boom load rating chart for simplifying the calculation of the load rating for any given boom extension distance of the boom apparatus.
2. Discussion of the Prior Art
A color coded boom and chart system is disclosed in U.S. Pat. No. 4,211,332, to Pitman. In this known device, a truck mounted crane is provided with a boom having multiple stages which are sequentially extendable such that when it is desired to extend the boom, intermediate and outer boom stages are moved together relative to the inner boom stage until the intermediate stage is fully extended, at which time the outer stage continues to extend until it reaches its fully extended position. Each of the stages is colored relative to the other stages, and a correspondingly colored chart is included on the truck for simplifying the procedure used to determine the magnitude of a load that may be safely carried by the boom at any given angle and extension distance thereof.
Although the color coded boom and chart system disclosed in U.S. Pat. No. 4,211,332 simplifies the interpretation of load rating charts as compared with prior known systems, it would be desirable to further improve the color coded system to permit the use of the system with boom constructions including proportionally extended boom stages which move simultaneously during extension and retraction of the boom. In addition, it would be advantageous to further reduce the number of steps necessary in determining the load rating of a boom at any given angle and boom extension distance while increasing the accuracy of the system to include substantially more load rating data than in known systems.